It is too early to be worried, as it may take some time to have the first pregnancy. If your wife has a regular menstrual cycle, then you may know which days would be more important to have sex in order to have a better chance of pregnancy. Subtract 14 from the total menstrual cycle length and most likely she is ovulating near that day. For example, if she has a regular 30-day cycle, then most likely she is ovulating on day 16th. So, if you have regular sex on day 15, 16 and 17 and wife does not clean her of the semen too quickly, your chances would increase. However, there is no guarranty that will work at all time. It takes some time for the testes to produce sperms, so you may consider not having sex on day 13 and 14, which at least will increase semen volume.
There is no problem if whatever semen is left in the vagina comes out few hours after sex.